


Need

by CleverUsernameHere



Category: Supernatural
Genre: Age Swap, Alpha Dean Winchester, Alpha/Beta/Omega Dynamics, Anal Sex, Bottom Sam, Knotting, Loss of Virginity, M/M, Masturbation, Mating Cycles/In Heat, Omega Sam Winchester, Plot What Plot/Porn Without Plot, Sex Toys, Top Dean Winchester, possible dubcon but only if you think too far into it
Language: English
Status: Completed
Published: 2020-04-23
Updated: 2020-05-02
Packaged: 2021-02-23 07:31:10
Rating: Explicit
Warnings: Underage
Chapters: 2
Words: 4,757
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23808025
Author URL: https://archiveofourown.org/users/CleverUsernameHere/pseuds/CleverUsernameHere
Summary: Dean presents as alpha and goes into his first rut at the age of 16. His omega brother, Sam, is there to take care of him like an older brother should. That is until Sam goes into heat and neither of them can think clearly.
Relationships: Dean Winchester/Sam Winchester
Comments: 39
Kudos: 315
Collections: SPN ABO Bingo Round 5





	1. Chapter 1

**Author's Note:**

> Usually my fics are very plot-heavy but I went opposite for this. It’s smut just for the sake of smut. The plot is very minimum, this fic is straight up porn.
> 
> Part one fills my omega!sam square for SamWinchesterBingo on my tumblr

Sam had scented what was going on with Dean before Dean even knew. He had been complaining of feeling too warm and got aggressive with Sam when he tried to calm him down.

“You’re presenting, Dean.” Sam explained, pressing the back of his hand to Dean’s forehead to feel for a fever. 

He knew Dean was alpha just by the smell of it, although Sam himself had never dealt with an alpha rut since he was an omega. The only alpha he’d ever been around for a long period of timewas his father, but John always disappeared during his rut. Sam has no idea how to help.

“I realize that.” Dean snapped in frustration, swatting Sam’s hand away. He pushed himself to sit up and ripped his t-shirt over his head. “‘S too hot in here. Doesn’t it feel too hot?” Dean grunted out, wiping his chest and under his arms with the shirt before discarding it. “How do I make this stop? Feels like I’m burning.”

“Relax, just breathe.” Sam hushed, it was his natural instinct to try and help calm the alpha. Dean just shot him a glare and muttered something Sam couldn’t hear.

“I can’t relax.” Dean said louder with a shake of his head. “It’s too hot in here- my body feels like it’s on fire. You’re crowding me and your scent is too strong- just back up!” Dean spoke quickly, eyes wild, clearly unable to focus on one thing at a time. “Can’t think straight.” 

“I’ll just… sit over here.” Sam said calmly, holding his hands up in defense as he moved away from the bed. 

Sam found a chair and pulled it up beside Dean’s bed. He took a seat and looked to Dean, who thanked him quietly with a sigh. Sam understood that everything could feel overwhelming with a presentation, so he didn’t take personal offense.

Dean had just turned 16, he was right on schedule. Sam had presented around the same time, although as an omega. He remembered with no fondness at how much pain he’d been in during his first heat.

Sam wished he could help Dean more. He told himself that he should’ve researched alpha presentations ahead of time. Now he didn’t have time because he couldn’t leave Dean alone to go to a library or anything. Their dad was gone, leaving them at the rented house on their own. Sam, without help, couldn’t think of more to do other than to bring Dean food and water and keep him as comfortable as possible.

“Could you get me an ice pack or something?” Dean asked, wiping sweat from his forehead and out of his eyes with the back of his hand. “And, uh, turn the air up?”

Sam didn’t bother to tell Dean that the AC was on full blast because he knew it wouldn’t make a difference. “Sure.” Sam just offered a smile and stood, heading out of the room. The kitchen was just down the hall, but Sam made sure to leave the door wide open in case Dean needed anything else.

Sam grabbed an ice pack from the freezer and a water bottle from the fridge. A sudden jolt of pain sparked in Sam’s abdomen and he gasped, dropping the water and ice in favor of gripping the fridge door handle for balance. He grit his teeth and forced himself to stand, placing a hand over his belly at the sudden pain.

“Damnit, no.” Sam winced out, his fingers digging into his skin as he took a deep breath. This is not at all what he needed right now. His heat was weeks away, he was supposed to be fine. He needed to be able to look after Dean.

That’s when it hit Sam. Being around Dean during his presentation must’ve forced his heat. Dean’s rut would be coming in only a matter of hours and the omega side of Sam had to have sensed that.  
He decided at that moment to grab some sedatives for Dean before picking up what he had dropped. 

Dean was apparently already overwhelmed by his scent, Sam wasn’t sure how it would affect his younger brother if he was in heat. It would be a lot easier on both of them if Dean could sleep for a while until Sam figured out how to take care of Dean and himself.

When Sam returned to Dean’s room, his cheeks flushed pink. Dean’s back was pressed to his headboard, his head was tipped back with his eyes shut, and his hand was palming the bulge in his pants.

Dean’s eyes snapped on and he yanked his hand away from himself. He looked to Sam briefly before glancing away. “Sorry.” Dean wasn’t sure what else to say.

“It’s fine. I get it.” Sam said quickly, trying not to look at the bulge in Dean’s pants. “I got water, an ice pack, and some pills.” Sam listed off as he handed them off to Dean.

“Pills?” Dean eyed the blue tablets suspiciously. “What are these? They don’t look like our painkillers.”

“I’m not gonna poison you or anything.” Sam chuckled and Dean rolled his eyes. “Sedatives. They’ll help you sleep and, uh, calm you down for when your rut comes.” Sam said awkwardly. “Which I guess is gonna be sooner than I thought.”

“Never been so hard in my life.” Dean said as if it was casual before taking the pills and chugging the water. Sam, on the other hand, blushed further at the thought.

“Have you been able to… y’know?” Dean furrowed his brows at Sam’s question. Then he saw Sam’s eyes drop to his lap before snapping back up to his face.

“Get off?” Dean snorted in a bit of laughter. “You’ve kinda been hovering. Haven’t exactly had the chance.”

“Right, sorry.” Sam swallowed, wincing when another cramp struck him.

“You okay?” Dean asked and Sam furrowed his brows in concentration and placed a hand just below his belly. “Are you hurt?”

“Yeah- no- sorry. I’m fine, I just,” Sam took a deep breath. His heat was coming a lot quicker than he thought. Sam could already feel slick forming between his legs after being near the younger alpha. It didn’t matter that Dean was his brother, the omega in Sam was reacting to Dean’s alpha rut. “You rest and I’m gonna go lay down.” Sam decided, realizing that him being near Dean would only make the young alpha’s rut worse.

“Sam?” Dean called after his brother as he disappeared down the hall. “Weirdo.” Dean muttered and reached for the ice pack. He kicked off his pants and scooted down his bed before placing the ice pack on his forehead.

Sam scurried to his room and closed the door behind him. He would’ve locked it if he could. Sam was hurting, his heats were always bad. 

Unfortunately, he had just given the last sedative pills to his brother. Although, Dean needed them more than he did. Sam knew how to handle his heat more than Dean did his rut.

Sam hurried to his dresser drawer and pulled it open. He dug through his clothes until he found what he needed. A silicone dildo with a thick knot on the bottom to help him through his heats. Sam had never had the real thing, but even though the toy was fake, it always helped.

Sam’s cock was hard in his pants, enough precum dripping that he could feel the wetness inside of his boxers. Slick was also dripping from his hole- Sam knew he’d be ready. He just wanted to make the heat pains stop quick so he could rest and get back to helping Dean without a clouded mind or heat pains.

Sam dropped the toy on his bed and started to strip off his shirt. His clothes felt too constricting. Sam quickly moved to his pants, pushing them and his boxers down his legs. He whimpered when he felt a trail of slick slide down his inner thigh. Sam couldn’t remember the last time he’d been so wet and ready so fast. He tried to not think about the fact that it was his own brother who had that effect on him.

Sam had never thought about Dean that way before, but now he couldn’t get the idea out of his head. He had never been around an alpha in a rut before and his omega side wanted to run back to Dean. Sam threw himself down onto his bed instead of giving into the urge to rush back to Dean’s room and impale himself on his brother’s alpha cock.

Sam grabbed for the toy blindly and when he found it, he lined it up to his entrance. He didn’t have the time or the desire to draw this out longer than he had to. He planted his feet onto the mattress and spread his legs wide. Sam whimpered in pleasure as he pushed the toy inside of his ass. He took it easy, barely feeling the delightful stretch as he thrust it in.

Sam took a deep breath, but he was far to horny to relax. Sam gripped the base and withdrew the toy before shoving it back in. His eyes fluttered shut and his jaw dropped, silently gasping in bliss. His cock twitched and precum dripped down and pooled on his belly below. Sam knew he could finish quickly, all he wanted was to get off anyway.

Sam gripped the base of the toy and withdrew it slowly, whining at the drag. The toy was on the smaller side in length, only 6 inches long, but it was thick around. Sam hadn’t known what he liked when he’d gotten the toy, he had just wanted something to help through his heats.

Sam pushed it back inside of himself and he whimpered, pulling it back out again. When he shoved it back in, it rubbed against his sweet spot and Sam moaned loudly. He slapped his freehand over his mouth, not wanting Dean to hear.

That’s when Dean entered his mind. Sam kept working the toy between his legs, trying to focus on anything but his little brother taking the toy’s place.

And yet Sam couldn’t stop thinking about Dean’s strong alpha scent around him or his bigger-than-most teenage body draped over his. Dean was in a rut, he wouldn’t be gentle. Dean would be frantic, grasping at Sam’s hips, pushing his legs apart, and slamming his big cock inside of him. Sam knew by the bulge in his brother’s pants that he wasn’t small. He’d give Sam what he needed better than the fake cock ever could.

Sam worked the toy faster, images of his alpha brother flashing in his mind. Sam was so close.  
He imagined Dean growling in his ear, telling him how good he smelled and how tight he was. If Sam focused enough he could actually hear Dean saying those things.

“Alpha!” Sam whined out, shoving the entirety of the toy inside of himself. The stretch of the fake knot combined with the pressure on his prostate and the thoughts of Dean all worked together to push him over the edge.

Sam gasped loudly into his own hand when he came. His eyes went wide and his head tipped back as his cock spilled his release onto his own belly. Sam’s whole body shook, his thighs quivering as he held the toy deep, feeling the knot stretching his hole. Sam started again, slowly thrusting the toy inside of himself to ride out his orgasm.

When he finally came down from his high, Sam withdrew his hand from his mouth. He took a few breaths before relaxing into the mattress.

Sam let go of the toy, leaving it stuffed inside of himself. He liked the feeling of the fake cock filling him up and the knot stretching him out. Sam allowed his legs to drop to the bed and he whimpered as the toy shifted inside of him. He clenched down, shifting his hips. His cock was softening already, but Sam didn’t touch himself there either. Everything below his waist was still far too sensitive.

A wave of exhaustion crashed over Sam as he steadied out his breathing. He always felt tired after coming, so much so that he didn’t bother to clean up or even move. Instead he rested back against the bed and closed his eyes, images of the alpha just a few rooms away filling his head.


	2. Chapter 2

**Notes for the Chapter:**

> This chapter fills my ‘first knot’ for my Spn abo bingo and my ‘free space’ for DeanSam bingo on my tumblr @slut-for-Jared

Dean’s cock was still aching in his boxers when he woke up. With a groan he reached down to rub at his bulge, his cock was absolutely throbbing for attention.

Dean took a deep breath and inhaled the most amazing thing he had ever smelled. It was the same scent that often surrounded Sam, but it was so much stronger now. Much more powerful than Dean could’ve imagined, like it was amplified by a hundred.

Dean had always thought Sam smelled good in the past, but now it was intoxicating. He arose from bed, not bothering to redress himself. In nothing but his boxers, Dean crept down the hall towards Sam’s room. He needed to be close to his brother. Dean told himself all he needed was to surround himself with Sam's sweet smell and he would be fine.

Sam’s door was closed, but it was only a minor obstacle. Dean debated knocking, but instinct took over. His need to be near the omega and that sweet scent took over. 

Dean pushed the door open and his jaw dropped at the sight. Sam was completely naked, sprawled out on his bed, flat on his back, above the covers. Sam looked dead asleep and Dean thought about closing the door to pretend he hadn’t seen anything, but something pushed him forward instead. 

Normally he would’ve been embarrassed for both him and Sam at what he was seeing, but his body reacted in a way it never had before. Dean’s whole body flushed with arousal at the sight of his brother. Dean didn’t question himself, he wasn’t in the right mind to. His newfound alpha side was in complete control and his alpha side wanted the omega more than anything. It didn’t matter that Sam was his big brother.

Dean looked closer and he saw Sam’s belly was coated his own cum beneath his soft cock. Dean knew about male omegas and how they tended to be smaller, well, everywhere. But Sam was bigger than the average omega in every way and Dean couldn’t help but be impressed.

When Dean stepped closer and he looked between Sam’s legs, his cock throbbed in his boxers. Between Sam’s round ass cheeks Dean could see something sticking out. 

Dean kneed his way onto the bed without thought, placing himself between Sam’s long, spread legs. Dean cast his eyes up at Sam’s face, noting that he was still asleep. He told himself he was just curious when he reached down between Sam’s spread legs and poked the base of what he quickly realized was a sex toy. Dean was young, but not naive.

Dean couldn’t come up with an excuse for why he gripped the base of the toy. It was slick under his fingers and Dean bit his lip. He knew it was from Sam. His brother must’ve gone into heat. Dean could smell it and the effect on him was a lot more powerful. 

The thought of Sam being in heat and so desperate that he ran from Dean’s room to his own and fucked himself with the fake cock so hard he came all over himself and probably passed out was divine. Dean couldn’t stop himself from groaning aloud. 

Controlled by his rut’s desire for the omega, Dean tugged at the toy. Sam flinched in his sleep, but didn’t wake up. Dean took that as a sign to keep going. His mind was clouded with lustful curiosity. Dean wondered how big the fake toy was.

Dean growled at the thought of Sam having done this enough with other alphas to be experienced. His reaction surprised him, not understanding the sudden possessive feeling he had for Sam. Dean only knew enough to blame it on his rut.

A loud whine fell from Sam’s lips when Dean tried pulling at the toy once more. The fake knot tugged at Sam’s hole and Dean grew frustrated. He roughly yanked it back and the fake knot slipped out of Sam’s slick hole. Dean couldn’t describe the feeling as anything other than relief when he realized it wasn’t as big as he had thought.

Dean pulled the rest of the toy out and Sam whimpered in his sleep. Dean measured its length with his eyes and he smirked to himself. He was definitely bigger than the stupid toy. Dean tossed it aside on the bed, not liking the idea of anything else being inside of Sam.

Fresh slick dripped from Sam’s ass and Dean marveled at the sight. Dean looked up to Sam’s face and noticed his brother’s nose twitching. Then Sam’s eyes fluttered open and if Dean hadn’t been so lost in his rut, he would’ve apologized and left. But something inside of him was keeping him in place, not daring to leave, even as Sam’s eyes locked with his.

“Dean?” Sam asked weakly. “What are you doing?” Sam didn’t sound embarrassed or even betrayed like Dean thought he would’ve been. He just sounded groggy and confused.

“Your scent, Sam. It’s just so strong. I- I tried to ignore it before.” Dean confessed, placing his hand on Sam’s thigh, pushing it up so he could get a better view between Sam’s legs. “I can’t ignore it anymore and- and seeing you like this?” Dean used his other hand to rub at the bulge in his boxers. He was harder than he thought possible, his cock aching to be buried inside of Sam’s warm, slick hole that was practically waiting for him. His knot was throbbing at the base of his cock, sending an incomparable jolt of arousal. “Need you bad.”

Sam nodded, understanding the desire yet unable to put it into words. He spread his legs wider for his little brother, whimpering as the intense alpha scent surrounded him. Sam felt like he was drowning in the power of it. Even if he wasn’t so dazed from his heat, Sam wasn’t sure if he would have been able to deny the alpha in his rut. 

Dean was far too eager to question his brother’s behavior. So he thanked whatever had given him this luck and pushed off his boxers. His hard cock slapped against his belly and Sam gasped. 

“Bigger than that toy, huh?” Dean grinned cockily and Sam nodded, his own cock twitching in attention. “You’re only gonna want my cock from now on, omega. I’m the only one who gets to be inside of you.” Dean didn’t know what came over him or where the dirty talk came from, but he couldn’t suppress his desire to have Sam be his.

Dean discarded his boxers and moved between Sam’s legs. He stroked his cock, smirking when he saw Sam’s cock was fully hard and his hole was dripping with slick. It was pooling on the blankets below him and Dean groaned, knowing he had that effect on the omega. 

Dean wasn’t sure exactly what he was doing, most it was just instinct guiding him. He ran the tip of his cock through Sam’s slick, pushing against his rim. Sam bucked his hips down and Dean licked his lips.

“Have you ever done this?” Dean couldn’t stop himself from asking.

“No… have you?” Sam asked almost shyly, his cheeks tinted pink. 

“I’ve done… stuff. Not this. You’re my first for this.” Dean pressed the tip of his cock to Sam’s slick entrance. “And I’m your first.” Dean whispered in near awe to himself, watching with undivided attention and he pushed inside of his brother. 

The second he was inside of Sam, Dean lost control. He snapped his hips forward and buried his cock deep inside of his big brother. Sam moaned, the feeling of Dean’s cock being much better than he’d ever expected. Sam was so slick and prepped from the toy that he took Dean to the hilt, but that didn’t stop him from feeling the thick drag of Dean’s cock thrusting inside of his ass and stretching him out.

The young alpha groaned and fell forward, collapsing over Sam. He clung to his older brother, sucking in ragged breaths. Nothing could have prepared Dean for the amazing feeling of being completely inside of Sam’s tight, warm, slick omega hole. Dean’s cock twitched and his knot pulsed. He didn’t know if he’d even be able to last.

“Dean?” Sam asked breathlessly, reaching down to stroke his little brother’s hair. “You alright?” Sam panted out, trying to ignore his own intense pleasure to make sure Dean was alright. 

“Really good.” Dean muttered out, the tip of his nose grazing against Sam’s chest as he took a deep breath. “Feels good.” Dean bucked his hips forward and Sam whimpered.

Sam wanted Dean to move. The alpha cock felt so good inside of him, filling him up and stretching out in ways Sam had never experienced before. His body clenched around Dean’s thick cock and his cock twitched from where it was trapped between him and Dean. Sam was ready, his body was getting needy.

Thankfully, Dean seemed to be feeling the same way. He pushed himself off of Sam’s body. Dean gripped Sam’s hips and pulled back. Then he gave an experimental thrust forward, burying his length in Sam once more. The action drew a moan from the omega and pleasure coursed through Dean at the feel and the sound. He liked that he could make Sam feel as good as he felt.

Dean repeated that action, pulling out of Sam before thrusting forward. Sam moaned louder and Dean didn’t stop. He held Sam’s hips hard, thrusting his thick cock in and out of his older brother.

“Feels so good, alpha.” Sam panted, his words encouraging his younger brother. 

It felt like heaven to Dean, feeling Sam around him. He never knew pleasure like this could exist. He kept thrusting, kept fucking into Sam at in increasing speed. Sam was gasping and moaned below him, his head tipped back and his jaw agape. 

Dean was grunting like an animal, shoving his cock into Sam as deep as he could over and over as fast as he could. He chased his release, the need to feel his knot fully formed and locked inside of Sam overtaking everything.

“‘M not gonna last.” Dean grunted out honestly, digging his fingers into Sam’s skin. There would be bruises on the older omega’s hips, but neither of them seemed to care. “Want you to cum, Sam, but my- my knot. I need-“

“I know.” Sam nodded and gasped. His eyes fluttered shut in pleasure when Dean hit his sweet spot dead on. “Oh! Right there, alpha. Just- just keep going.” Sam pleaded. It felt so good, Sam was so close. 

Dean took in Sam’s words and followed through, thrusting in the same position. Whatever he was doing, it was having an incredible effect on Sam. Dean didn’t fully understand, but Sam was moaning louder and clenched down around his cock. It made him feel so much tighter and clearly brought him pleasure, so Dean persisted. He focused his attention on fucking Sam hard and fast at that same angle.

Suddenly, Sam’s whole body tensed and he moaned loudly. His hands fisted the blankets beneath him as his back arched off of the bed. His thighs quivered and Dean kept thrusting. He watched in awe as Sam’s cock twitched before he came, seed spilling against his own belly. 

Dean just made his big brother come from nothing but his cock, he couldn’t believe it. His chest huffed with pride, knowing that he’d brought the pleasure to the omega. Before he wouldn’t have even thought of doing this with Sam, but Dean knew from now on all he would be able to think about was how good Sam felt and how pretty he looked when he came all over himself. 

“Gonna knot you.” Dean growled out and started thrusting faster.

“Wait a second,” Sam said breathlessly. He tried to sit up and Dean snarled, his hands slapping against Sam’s chest and shoving him back down to the bed.

“Can’t stop, please don’t make me.” Dean grit out, trying to make himself slow down. If Sam wanted him to stop, Dean would. He never wanted to hurt his brother, even if the mere thought felt like it would kill him.

“It’ll be easier if I’m on my hands and knees.” Sam responded calmly in response to Dean’s aggression. Dean stilled his hips. His knot was throbbing, seconds away from popping. His cock was twitching and his balls felt heavy, full of cum that he needed to spill inside of Sam.

Dean pulled out quickly and used his newfound alpha strength to roll Sam onto his stomach. Sam gasped in shock when Dean gripped his hips and pulled his ass up. Dean then thrust back in and groaned at the new angle. His cock felt like it was hitting so much deeper this way.

Dean picked up his rhythm again, thrusting into Sam hard and quick. His hips slammed against Sam’s ass and the sound, paired with Sam’s moans and Dean’s groans, filled the room. It was like Dean was in his own bubble of pleasure.

“Cum inside of me.” Sam urged, words muffled by the pillows. Dean growled and fucked into him harder, thrusting his hard cock into Sam as deep as he could.

Suddenly, his hand shot to Sam’s hair. Dean gripped it tight and tugged, pulling Sam’s head off of the pillows. “Say it again.” Dean growled out, thrusting hard to punctuate each word. “Call me alpha.”

“Cum inside me, alpha.” Sam begged like Dean wanted and the young alpha groaned. “Fill me up. Give me your cum, please!” Sam had never felt such an intense need before. Neither of them had. Sam needed to be filled and Dean needed to be the one to do it.

The words pushed Dean over the edge. He shoved into Sam to the hilt. His knot popped and Dean yelped in surprise at the intense pleasure. His cock twitched and pulsed inside of his big brother, his cum gushing and filling Sam up.

The real knot from his brother was nothing like Sam’s toy. Dean’s knot was nearly the size of a fist, shoved inside of him and locked tight. Rope after rope of Dean’s cum flooded Sam’s insides, the full feeling only furthered by Dean’s cock and knot being trapped inside of his hole. Sam knew that the toy had been ruined for him, it could never feel as good as Dean did. 

Dean slumped forward, his chest pressed to Sam’s back. Dean tucked his arms around Sam and nuzzled his head on Sam’s shoulder. “Never felt so good in my life.” Dean sighed out in dazed content, his rut finally satisfied.

“Can we lay down?” Sam asked quietly and Dean nodded against his back, too lost in his own intense pleasure to actually comprehend Sam’s words. 

Sam moved onto his side and Dean went with, clinging to the bigger omega, not wanting to part with him. Dean gave his hips and experimental thrust forward before pulling back. Sam whined at the feel of the thick knot tugging at his rim. Dean stilled after that, relaxing, knowing that he could stay connected to the omega.

“How long is this gonna last?” Dean asked curiously, running a hand over Sam’s reddened ass and up his slender hip. Dean couldn’t believe that he had never admired the omega in this way before. 

“Probably a while.” Sam hummed in content, pushing his ass back. There was nothing compared to the feeling of a real alpha knot. “You tired?” Sam asked sleepily. He heard Dean hum in confirmation behind him, his little brother’s arms tucking around his torso.

Dean was already falling asleep and Sam smiled softly to himself. It wasn’t exactly what he thought of when taking care of Dean, but he found himself enjoying the feeling of being in his little brother’s arms. Sam didn’t even think to wonder what would happen when they both came out of their primal, lust-ridden haze.

**Notes for the Chapter:**

> Kudos are awesome but comments are like gold to me! Even a simple few words can inspire me to write more fics!

**Author's Note:**

> Kudos are awesome but comments are like gold to me! Even a simple few words can really motivate me to write more :)


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